The invention relates to apparatus and a method for monitoring the laying of a pipeline, and particularly where the pipeline is laid from a vessel onto the seabed.
Conventionally, when a pipeline is laid from a vessel such as a reel barge or a lay barge, there is usually a survey vessel in addition to the lay or reel barge, in order to monitor the touch down of the pipe onto the seabed. The survey vessel would typically have an ROV which carries sonar and stereo video equipment which is deployed in the region where the pipe is being laid.
However, the requirement of this survey vessel, and associated ROV equipment, increases the cost of laying a pipeline. In addition, the lay or reel barges can usually continue to lay the pipeline in worse weather conditions than the survey vessel can operate in. Thus, the survey vessel may halt the pipeline laying operation in situations where the reel or lay barge is capable of continuing.
According to a first aspect, the present invention provides apparatus for monitoring the laying of an underwater pipeline, the pipeline being laid from a pipeline dispenser, the apparatus comprising a body member; a monitoring means connected to the body member for monitoring the pipeline as it is laid; the body member being moveable with respect to the pipeline; and a means to position the body member a distance from the pipeline dispenser.
According to a second aspect, the present invention provides a method of monitoring the laying of an underwater pipeline, the method comprising providing a body member moveable relative to the pipeline; providing a means to position the body member a distance from the pipeline dispenser, the body member having monitoring means associated therewith, and paying out the pipeline from the pipeline dispenser, such that the monitoring means provides data with respect to the pipeline as it is laid.
Preferably, the coupling means maintains a distance between the pipeline dispensing mechanism and the body member, and more preferably, the maintained distance is known. Typically, markings are located along the length of the coupling means to indicate the distance between the pipeline dispensing mechanism and the body member.
Typically movement means are provided, preferably on the body member, to assist movement of the body member with respect to the pipeline. The movement means may be a roller mechanism.
Preferably, the pipeline dispensing mechanism is mounted on a vessel at the water surface, where the pipeline is laid from the vessel onto the seabed and typically, the apparatus further comprises a transmission means for transmitting data output by the monitoring means to the vessel.
The body member may be coupled to, or in contact with, the external surface of the pipeline, or alternatively, the body member may be coupled to, or in contact with, the internal surface of the pipeline. Where the body member is in contact with the external surface of the pipeline, the body member may comprise a bore, whereby the pipeline is moveable through the said bore. The monitoring means may comprise a sonar transmitter and a sonar receiver. Alternatively, or in addition, the monitoring means may be a visual viewing means, and may be a video camera.
The body member may comprise a buoyancy means. Alternatively, or in addition, the body member may comprise a self righting means. The apparatus may monitor the pipeline that has passed through the bore of the body member. A second body member may be provided that allows the apparatus to monitor a portion of the seabed prior to the pipeline being laid on that portion of the seabed.
Where the body member is movably coupled to, or in contact with, the internal surface of the pipeline, the body member may be moveable through the internal bore of the pipeline. The monitoring means may be an inertial attitude sensor. The monitoring means may provide for monitoring of variation of the longitudinal axis of the pipeline and the monitoring means may be a pipeline buckle detector.
Typically, a body member is located within the pipeline at the location where the pipeline first makes contact with the sea bed.
The apparatus may further comprise a selective sealing device, interposed in the length of the connection device, which seals the pipeline when operated. Typically, the selective sealing device is an explosive welding device.
According to a third aspect of the present invention there is provided a pipeline sealing device comprising a body member for insertion into a pipeline, and an explosive material associated with the body member, such that triggering of the explosive material expands the body member to seal the internal bore of the pipeline on one side of the body member, from the internal bore of the pipeline on the other side of the body member.
Preferably, the body member comprises a cylindrical member, whereby the explosive material is mounted within the cylindrical member. Typically, the cylindrical member comprises an inner bore which extends into the cylindrical member at one end, and a sealed other end. Preferably, the explosive material is mounted on the inner bore of the cylindrical member. Typically, the cylindrical member is a clearance fit with the inner bore of the pipeline. Preferably, the pipeline sealing device is moveable along the internal bore of the pipeline, and more preferably is coupled to a connection device which moves the pipeline sealing device. Most preferably, the pipeline sealing device is coupled to a connection device of an apparatus for monitoring the laying of an underwater pipeline in accordance with the first aspect of the present invention.
According to a forth aspect, the present invention provides an apparatus for deploying an elongate member within a conduit, the apparatus comprising a body which is coupled to the elongate member, the body being moveable along the longitudinal axis of the conduit, and a positioning means which maintains the body substantially in a known position within the conduit.
According to a fifth aspect, the present invention provides a method of deploying an elongate member within a conduit, the method comprising inserting a body into the conduit, the body being coupled to the elongate member, and the body being moveable along the longitudinal axis of the conduit, and paying out the conduit from a dispenser, the body being maintained substantially in a known position within the conduit by a positioning means.
Typically, the conduit is a pipeline, and preferably, the pipeline is laid onto the seabed from a pipeline dispenser which is typically located at or adjacent the water surface.
Preferably, the body is located within a first portion of the pipeline which is vertically lower than second and third portions of the pipeline adjacent both ends of the first portion.
Preferably, the weight of the body is greater than the weight of the elongate member coupled to and acting upon the body. The invention has the advantage that the weight of the body maintains the body within the first portion of the pipeline as the pipeline is dispensed from the dispenser.
Typically, there is no connection between the body and the dispenser.
Typically, at least one, and preferably more than one, body members are coupled to the elongate member, and a monitoring means is typically mounted on, or connected to the body member for monitoring the pipeline as it is laid underwater and the monitoring means typically comprises a data output.
Typically, the distance between the body and the body member(s) is fixed by the elongate member, such that when the body is stationary with respect to the pipeline, the body member(s) is/are also stationary.
Preferably, the pipeline dispensing mechanism is a reel whereby the pipeline is coiled around the reel prior to dispensing thereof.
Preferably, the movement means permits the body to move substantially freely with respect to the pipeline.
Preferably, movement of the body with respect to the conduit in the radial direction of the conduit is resisted.
In addition, the coupling means further comprises a motive mechanism which permits the body to travel through the pipeline, and to pull the elongate member through the pipeline.